1. Field of the Invention
The present invention is directed generally to wireless signal transmission, and, more particularly, to wireless signal transmission in a building heating, ventilation, and air conditioning (HVAC) system.
2. Description of the Background
Wireless transmission of electromagnetic radiation communication signals has become a popular method of transmitting RF signals such as cordless, wireless, and cellular telephone signals, pager signals, two-way radio signals, video conferencing signals, and local area network (LAN) signals indoors. Wireless transmission indoors has the advantage that the building in which transmission is taking place does not have to be fitted with wires and cables that are equipped to carry a multitude of signals. Wires and cables are costly to install and may require expensive upgrades when their capacity is exceeded or when new technologies require different types of wires or cables than those already installed.
Traditional indoor wireless communications systems transmit and receive signals through the use of a network of transmitters, receivers, and antennas that are placed throughout the interior of the building. These devices must be located in the interior structure such that the signals are not lost or the signal strength does not diminish to the point that the data being transmitted is unreliable. The placement of the devices becomes more complex when portable receivers, such as laptop computers, are integrated into the communications system.
Due to the variations in architecture and types of building materials used in different structures, the placement of transmitters, receivers, and antennas is very difficult. Wall board, steel studs, metallic air ducts, electrical conduit, plumbing, etc. all have an effect on wave propagation in a structure. Methods to determine optimal placement of communications system components to account for wave reflection and absorption include ray tracing, which uses geometrical optics and diffraction to model the propagation of waves through a structure. Statistical channel modeling, which attempts to characterize the general indoor channel by determining the most appropriate distributions for a set of channel parameters, can also be used. Despite these methods, the placement of communication systems transmitters, receivers, and antennas is still largely a process of trial and error.
Many communication systems are thus implemented inefficiently. High power or redundant transmitters are often positioned to ensure full coverage of the structure. Furthermore, a change in position of objects such as metal desks, metal filing cabinets, etc. that are placed in a room can affect the transmission or reception in that room.
Thus, there is a need for a method and a system for efficiently transmitting electromagnetic radiation signals such as RF waves, microwaves, and infrared radiation indoors without having to install an extensive system of wires and cables in the building. Also, there is a need for a method and a system for efficiently transmitting electromagnetic radiation signals indoors without having to design an elaborate system of transmitters, receivers, and antennas that may not have optimal placement.